How TO - JavaScript HTML Animations
Learn how to create animations using JavaScript.
A Basic Web Page
To demonstrate how to create HTML animations with JavaScript, we can use a simple web page.
Example
<!DOCTYPE html>
<html>
<body>
<h1>My First
JavaScript Animation</h1>
<div id ="myContainer">
<div id ="myAnimation">My
animation will go here</div>
</div>
</body>
<html>
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Styling the Elements
To make an animation possible, the animated element must be animated relative to a "parent container".
The container element should be created with style = "position: relative".
The animation element should be created with style = "position: absolute".
Example
#myContainer {
width: 400px;
height:
400px;
position: relative;
background: yellow;
}
#myAnimation {
width: 50px;
height:
50px;
position: absolute;
background: red;
}
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The Animation Code
JavaScript animations are done by programming gradual changes in an element's style.
The changes are called by a timer. When the timer interval is small, the animation looks continuous.
The basic code is:
Example
var id = setInterval(frame, 5);
function frame() {
if (/*
test for finished */) {
clearInterval(id);
} else {
/* code to change the element style */
}
}
Create the Animation Using JavaScript
Example
function myMove() {
var elem =
document.getElementById("myAnimation");
var pos = 0;
var id = setInterval(frame,
10);
function frame() {
if (pos ==
350) {
clearInterval(id);
} else {
pos++;
elem.style.top = pos + 'px';
elem.style.left = pos + 'px';
}
}
}
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